mhtree.VFV {mclust1998}R Documentation

Classification tree for hierarchical clustering for Gaussian models with equal volume and constant shape.

Description

Computes a classification tree for agglomerative hierarchical clustering using a Gaussian model in which clusters have a constant shape and are of equal volume.

Usage

mhtree.VFV(data, partition, min.clusters = 1, shape, alpha = 1)

Arguments

data matrix of observations.
partition initial classification of the data. The default puts every observation in a singleton cluster.
min.clusters minimum number of clusters desired. The default is to carry out agglomerative hierarchical clustering until termination, that is, until all observations belong to a single group. The default value is 1.
shape positive vector of length equal to the dimension of the observations. The values of shape should be proportional to the squares of the lengths of the semi-major axes of the corresponding ellipsoid, and may be given in any order. Note that shape is a required argument.
alpha The value alpha times the trace of the sample crossproduct matrix of all the observations divided by product of the data dimensions, is used for the purpose of initalization. The default value is 1.

Value

an object of class "mhtree", which consists of a classification tree with the following attributes:

call a copy of the call to mhtree.VFV.
change value of the optimal change in likelihood at each stage.
dimensions the data dimensions.
initial.partition the partition at which agglomerative hierarchical clustering is initiated.

NOTES

The value alpha is needed because the criterion is not defined for singleton clusters or clusters consisting only of points that coincide.

References

J. D. Banfield and A. E. Raftery, Model-based Gaussian and non-Gaussian Clustering, Biometrics, 49:803-821 (1993).

C. Fraley, Algorithms for Model-based Gaussian Hierarchical Clustering, Technical Report No. 311, Department of Statistics, University of Washington (October 1996), to appear in SIAM Journal on Scientific Computing.

See Also

mhtree, mhclass, awe, partuniq

Examples

data(iris)
shape <- c(1,1/2,1/3)
mhtree.VFV(iris[,1:3], shape = shape)


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